Saw one in day light about a month ago. ..small metalic disk about the size of a car sorta, appeared out of nowhere hung for about 5 to 10 seconds in one place, did a small circle and accellerated away in the blink of an eye.

My guess is its easier to see the lights that they seem to display at night, obviously.

Think of all the useful light technology developed since the 1940's.

Surely they are multifunctional lights and not just put there to entertain you.